chrome: Cleanup class/struct forward declarations

chrome/browser/chromeos/chrome_browser_main_chromeos.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_CHROMEOS_CHROME_BROWSER_MAIN_CHROMEOS_H_
 #define CHROME_BROWSER_CHROMEOS_CHROME_BROWSER_MAIN_CHROMEOS_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "base/task/cancelable_task_tracker.h"
 #include "chrome/browser/chrome_browser_main_linux.h"
 #include "chrome/browser/chromeos/external_metrics.h"
 #include "chromeos/system/version_loader.h"
 
 namespace session_manager {
 class SessionManager;
 }
 
 namespace arc {
 class ArcServiceLauncher;
 }
 
 namespace chromeos {
 
 class ArcKioskAppManager;
 class DataPromoNotification;
-class EventRewriter;
 class EventRewriterController;
 class ExtensionVolumeObserver;
 class IdleActionWarningObserver;
 class LoginLockStateNotifier;
 class LowDiskNotification;
-class MagnificationManager;
 class NetworkPrefStateObserver;
 class NetworkThrottlingObserver;
 class PeripheralBatteryObserver;
 class PowerPrefs;
 class RendererFreezer;
-class SessionManagerObserver;
 class ShutdownPolicyForwarder;
-class SwapMetrics;
 class WakeOnWifiManager;
 
 namespace default_app_order {
 class ExternalLoader;
 }
 
 namespace internal {
 class DBusServices;
 }
 
@@ skipping 45 matching lines @@
 
   std::unique_ptr<LowDiskNotification> low_disk_notification_;
   std::unique_ptr<ArcKioskAppManager> arc_kiosk_app_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(ChromeBrowserMainPartsChromeos);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_CHROME_BROWSER_MAIN_CHROMEOS_H_